Installing Bundles with "Average" Docs

Let's do something fun! Google for SlackBundle - you'll find one called
nexylan/slack-bundle. This is a fun library that gives us a service that can
send messages to a Slack channel. To install it, find the composer require
line, copy that, move over to your terminal and paste:

composer require nexylan/slack-bundle php-http/guzzle6-adapter

Interesting: this installs the bundle and some other library called guzzle6-adapter.
Wait for it to install and... it fails!

Don't panic. There are two important things happening. First, this installed two
bundles! Cool! You can see both of them inside bundles.php:

15 lines config/bundles.php

... lines 1 - 2

return [

... lines 4 - 11

Http\HttplugBundle\HttplugBundle::class => ['all' => true],

Nexy\SlackBundle\NexySlackBundle::class => ['all' => true],

];

For the SlackBundle, it says "auto-generated recipe". That means that the bundle
doesn't actually have a recipe... but Symfony Flex, at least added it to bundles.php
for us. By the way, this is not necessarily a bad thing: sometimes a bundle doesn't
really need a custom recipe!

The second bundle did have a recipe. Before I started recording, I committed my
changes so far. To see what that recipe did, let's run:

git status

Interesting: it added a new configuration file called httplug.yaml:

15 lines config/packages/httplug.yaml

httplug:

plugins:

redirect:

preserve_header:true

discovery:

client:'auto'

clients:

app:

http_methods_client:true

plugins:

-'httplug.plugin.content_length'

-'httplug.plugin.redirect'

We don't know what this does, but it probably configures some sensible defaults.
Let's ignore it unless the docs tells us otherwise.

When composer require Fails

The second important thing I want to talk about is... well... this big error!

The child node "endpoint" at path "nexy_slack" must be configured.

Oof... this is not a great error message. It means that this bundle requires some
configuration, which we don't have yet. And since it didn't add a configuration
file via a recipe, we'll need to create it ourselves. But before we do that, the
most important thing to understand is this: when you see an error like this after
running composer require, Composer did finish successfully and the library was
installed.

Configuring the Slack Endpoint

Ok, let's go read the docs so we can figure out how to configure this bundle. Ah,
so one of the reasons that installing this bundle isn't smoother is that its documentation
is out-of-date! Hopefully it will be updated soon, but actually, this is a great
example of how to navigate less-than-up-to-date docs.

How do I know it's out-of-date? This AppKernel thing is a Symfony 3 concept.
We don't need to worry about enabling bundles: this is done for us automatically.

If you scroll down... ah, here is the configuration. And it says that this is
an example of default values... which probably means that we don't need to copy
all of this. Yep, we just need to fill in the parts that are required, so, endpoint.

Let's copy part of the configuration file. But... it doesn't tell us where to
put this! That's ok! We already know: it can live in any file in config/packages.
Let's create a new one called nexy_slack.yaml. Paste the config, but the only
key we need is endpoint:

3 lines config/packages/nexy_slack.yaml

nexy_slack:

... lines 2 - 3

If you're coding along, here's how this will work. First, you'll need access to
a Slack workspace where you're an admin. If you don't have one, you can create one:
it's free and easy.

Thanks to this, you now have a new Webhook URL, which anyone can use to send messages
to your Slack. There's no authentication - the URL is meant to be a secret. Um... yea,
I know you can read mine - I'm super bad at secrets. I'll invalidate it after I
record.

Again, starting in Symfony 4.0.5, you will not need to clear your cache when
adding a new config file.

What is $this->get()?

Sweet! The bundle is configured, so... how do we use it? Go back to the docs. Below,
yea! Usage! And this is where things get really interesting. The code says
$this->get('nexy_slack.client). What the heck is that?

Actually, this is something from Symfony 3... which we do not recommend doing in
Symfony 4 and may or may not work, depending on the situation. Basically,
$this->get() is, or was, a shortcut to fetch a service by its id. Instead of
doing this, we are - of course - going to fetch the service via autowiring.

You guys know the drill: find your terminal and run:

php bin/console debug:autowiring

And search for "Slack". Wait... nothing!

Yep... this bundle technically works with Symfony 4... but it hasn't been fully
updated. And so, it doesn't expose any services for autowiring! Right now, there
is no way to autowire that nexy_slack.client service.

We need to learn a little bit more about public versus private services. And
then take control of things with an autowiring alias!